1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor laser and particularly to a method preferably applied to manufacture of a ridge-stripe semiconductor laser having a current non-injection structure near an end face.
2. Description of the Related Art
There have been proposed nitride-based semiconductor lasers in which portions near both end faces of a resonator serve as current non-injection regions in order to suppress end face deterioration due to COD (Catastrophic Optical Damage) with increases in output (refer to, for example, Japanese Unexamined Patent Application Publication No. 2005-216990). The semiconductor lasers are shown in FIGS. 28 to 30.
In the semiconductor laser shown in FIG. 28, a ridge-shaped laser stripe, i.e., a ridge stripe 103, serving as a light-emitting portion is formed on a nitride semiconductor grown layer 102 grown on an n-type GaN substrate 101. The top of the ridge stripe 103 includes a p-type GaN contact layer 102a. 
The ridge stripe 103 is formed as follows. A tripe-shaped resist (not shown) corresponding to the ridge stripe 103 to be formed is formed on the nitride semiconductor grown layer 102. Next, the nitride semiconductor grown layer 102 is etched by dry etching using the resist as a mask to form the ridge stripe 103.
Next, a SiO2 buried layer 104 for a current-confining layer is formed over the entire surface, and then a portion of the SiO2 buried layer 104, which is disposed on the ridge stripe 103, is removed by etching. Next, a p-side electrode 105 is formed on the p-type GaN contact layer 102a at the top of the ridge stripe 103 so as to avoid regions near the end faces. Therefore, a region where the p-side electrode 105 is not formed is provided as a current non-injection region 106 near an end face of the ridge stripe 103.
In the semiconductor laser shown in FIG. 29, a SiO2 insulating layer 7 is inserted between a nitride semiconductor grown layer 102 and a p-side electrode 105 within a region near an end face of a ridge stripe 103. the nitride semiconductor grown layer 102 and the p-side electrode 105 are electrically insulated with the SiO2 insulating layer 107 to provide a current non-injection region 106 near an end face of the ridge stripe 103.
In a semiconductor laser shown in FIG. 30, boron (B) ions are implanted into a region of a p-type GaN contact layer 102a near an end face of a ridge stripe 103 to form a high-resistance region serving as a current non-injection region 106. Alternatively, dry etching damage is produced in a region of a p-type GaN contact layer 102a near an end face of a ridge stripe 103. Then, a p-side electrode 105 is put into Schottky contact with the region of the p-type GaN contact layer 102a where dry etching damage is produced, thereby forming a current non-injection region 106 near the end face of the ridge stripe 103.